Persistent reservations for virtual disk using multiple targets

A method of releasing a reservation for a virtual disk in a storage platform having a plurality of storage nodes on each of which are stored virtual disks, said method comprising:

• receiving a request at a first process on one of said storage nodes to release a reservation for a specific virtual disk in said storage platform, said request originating at a first virtual machine of a first remote computer and coming directly from a first controller virtual machine of said first remote computer;
• said first process requesting of a coordinator process on one of said storage nodes a lock for said specific virtual disk;
• receiving a second request at a second process on one of said storage nodes to reserve said specific virtual disk for a second virtual machine of a second remote computer different from said first remote computer, said second request coming directly from a second controller virtual machine of said second remote computer;
• said second process requesting of said coordinator process said lock for said specific virtual disk;
• said coordinator process giving said lock to said first process;
• and
• said first process resetting a current reservation holder field in persistent storage on one of said storage nodes that pertains to said specific virtual disk;

A method of preempting a reservation for a virtual disk in a storage platform having a plurality of storage nodes on each of which are stored virtual disks, said method comprising:

• changing a current reservation holder field of persistent storage on one of said storage nodes pertaining to a specific virtual disk to identify a first virtual machine of a first remote computer based upon a first request, said first request coming directly to said storage platform from a first controller virtual machine of said first remote computer;
• receiving a second request at a second process on one of said storage nodes to preempt a reservation for said specific virtual disk in said storage platform on behalf of a second virtual machine of a second remote computer different from said first remote computer, said second request coming directly from a second controller virtual machine of said second remote computer;
• said second process requesting of a coordinator process on one of said storage nodes a lock for said specific virtual disk;
• said coordinator process giving said lock to said second process;
• and
• said second process setting said current reservation holder field in persistent storage on one of said storage nodes that pertains to said specific virtual disk, said current reservation holder field being set to identify said second virtual machine.